The present invention relates to a battery housing device for use with various electronic instruments, and more particularly to a fixing structure for an electrode spring for electrically connecting positive and negative electrodes of a pair of batteries.
FIGS. 4 to 6 show such a battery housing device in the prior art, wherein FIG. 4 is an elevational view of the battery housing device; FIG. 5 is a plan view of FIG. 4; and FIG. 6 is an exploded perspective view of FIG. 4.
Referring to FIGS. 4 to 6, reference numeral 11 designates a battery case formed of plastics and configured as a rectangular box having an upper opening for permitting insertion of batteries. Reference numeral 12 designates one of lateral inside surfaces of the battery case 11. A plurality of ribs 15, 16 and 17 for retaining an electrode spring 14 (which will be hereinafter described) is provided in the vicinity of the lateral inside surface 12. These ribs 15, 16 and 17 extend upwardly from a bottom surface 13 of the battery case 11. The rib 15 is opposed to the inside surface 12 with a predetermined gap defined therebetween. The rib 15 is formed at its upper portion with a pair of cutouts 15a and 15b. The rib 16 is located at a laterally central position between both the cutouts 15a and 15b in such a manner as to bridge the rib 15 and the inside surface 12. A pair of the ribs 17 are located at positions below the cutout 15b at predetermined intervals in such a manner as to bridge the rib 15 and the inside surface 12. The electrode spring 14 is composed of a spiral turn portion 14a, a straight portion 14b extending horizontally from the spiral turn portion 14a, and a curved portion 14c continuing from the straight portion 14b and curved in a substantially U-shaped configuration. The spiral turn portion 14a serves as a negative electrode contactor adapted to contact a negative electrode of a first battery (not shown), and the curved portion 14c serves as a positive electrode contactor adapted to contact a positive electrode of a second battery (not shown) to be arranged aside the first battery.
In mounting the electrode spring 14 into the battery case 11, the spring 14 is inserted from the upper opening of the case 11 into the gap defined between the inside surface 12 and the rib 15. That is, a radially outermost turn of the spiral turn portion 14a is inserted into a space defined by the inside surface 12, the rib 15 and the rib 16, and is retained at three positions, i.e., opposite side edges and a lower end thereof by the inside surface 12 and the rib 15. The straight portion 14b is inserted into an upper recess 16a of the rib 16, and is retained by the inside surface 12 and the rib 15. The curved portion 14c is inserted at its U-shaped lower portion into a space defined between both the ribs 17, and is retained by the inside surface 12 and the rib 15. An upper end of the curved portion 14c is also retained by the inside surface 12 and the rib 15.
When a pair of batteries (not shown) are housed into the battery case 11 and arranged in such a manner that the polarity is countered, a negative electrode of one of the batteries contacts a radially innermost turn of the spiral turn portion 14a projecting inwardly from the cutout 15a of the rib 15, and is biased by an elastic force of the spiral turn portion 14a. A positive electrode of the other battery contacts the curved portion 14c exposed from the cutout 15b of the rib 15, and is biased against the curved portion 14c by an elastic force of another electrode spring (not shown). Thus, both the batteries are electrically connected in series through the spring 14.
However, the conventional retaining structure includes a plurality of ribs in the vicinity of the inside surface 12 of the battery case 11, so as to retain the electrode spring 14. Accordingly, a mold for molding the battery case is complicated in structure. Especially in the case of molding the battery case as a part of a case for an electronic instrument rather than individualy molding the battery case, the mold structure is further complicated, causing the necessity of division of the mold or use of many movable cores. As a result, the mold is rendered expensive. Further, as the electrode spring is also complicated in shape, a machining cost is increased.